Field
The invention relates to the field of biometric sensing and, particularly to measuring a physiological state of a person for fitness exercise.
Description of the Related Art
Heart-rate monitors and other biometric sensors are commonly used by professional athletes as well as by amateurs practicing exercising. Heart-rate monitors and other biometric sensors typically provide a user with information enabling efficient workout. A typical heart-rate monitoring system includes a biometric sensor attached to the body of the user and configured to measure heart rate of the user, to transmit the measured heart-rate to another device worn by the user (a wrist device, for example). The prior art also teaches systems where the wrist device itself includes the biometric sensor. The heart-rate information obtained with the biometric sensor is processed and displayed to the user. More advanced information, such as energy expenditure and fitness parameters of the user may also be calculated from the heart rate.
In heart rate monitoring, an aspect is to provide the user with information on the appropriate exertion level of an exercise. The exertion levels are typically characterized with heart rate zones, which tell the user appropriate values of heart rate at which the desired training response is achieved. The heart rate zones may be used for post-analysis of the exercise. In such case, the quality of the exercise is assessed in terms of how heart rate has accumulated at each heart rate zone. Furthermore, the estimated response to exercise is reported to the user. For example, if the heart rate primarily falls to the lower heart rate zones, the apparatus may indicate that the training effect was primarily associated with fat burning instead of improving fitness. If the exercise was carried out at higher heart rate zones, the apparatus may tell the user that the exercise was to improve maximum capacity. The heart rate zones may further be used as guiding tools during exercise. In such a case, the apparatus may show the user the currently used zone. The apparatus may show the user the target value for the accumulated time at each heart rate zone, and the user may change the exertion level such that the targets are fulfilled.
The user's adaptation capability to an exercise may vary between days, and therefore the user may benefit from day-specific exertion zones. Therefore, it is useful to consider alternative techniques to determine exertion zones for an exercise.